Bad news for those of you who value your anonymity. Researchers from the Massachusetts Institute of Technology and the Qatar Computing Research Institute just lit a torch over Tor’s dark web. The Daily Dot reports that researchers were able to analyze encrypted traffic patterns well enough to figure out not just which hidden websites Tor users visit, but the location of those sites, with up to 88 percent accuracy.

Tor is supposed to shield its users with layer upon layer of encryption and disperse information globally in an attempt to make tracing users impossible. Edward Snowden, for instance, trusted it to send information to The Washington Post. But researchers found that if you analyzed a single point in the network you can use it to track the location of the service.

Lucky for Tor, these researchers weren’t looking to exploit the service’s weakness and announced their results rather than compiling real information in order to map the dark web. In essence, they did a stress test and helped Tor developers diagnose their weakness. The test proved that Tor hasn’t always been impregnable, which means hackers or government agencies may already have troves of data (or not).

Tor could protect itself by masking the sequences so that all of them look identical and by sending out dummy packets.